The present invention relates to an ink container, in which fiber is placed as an ink retaining member for retaining ink, an ink jet apparatus employing such an ink container, and a manufacturing method for such an ink container.
As for a conventional ink container (whether it is integrated with a recording head, or it is exchangeable independently from the head) having been put to practical use for ink-based recording, there is a type of ink container filled with a single or a plurality of sponge pieces.
The sponge piece is placed in the ink container to prevent the ink from leaking out of a liquid ejecting portion such as a nozzle provided in a recording means. More specifically, it is placed there to use the capillary force peculiar to porous material such as sponge; the capillary force is used as back pressure for impeding the ink low directed toward the recording means. This back pressure creates negative pressure, relative to the atmospheric pressure, in the ejecting portion, and hereinafter, it will be referred to as xe2x80x9cnegative pressurexe2x80x9d.
Generally speaking the diameter of a sponge pore falls within a range of 80-200 xcexcm, and the sponge material itself occupies a substantial portion of the internal volume of the container. Therefore, as long as the sponge is present within the ink container, little can be expected from an attempt made to increase the amount of the ink, relative to the internal volume of a given ink container, that is, an attempt made to improve the space usage efficiency for the ink container.
Further, even when an effort is made to modify the structure of the ink container so that the amount of the ink, which otherwise ends up being left unused in the ink container, is reduced, the capillary force or the like of the sponge places an inherent limit to the reduction.
The porous material employed as the ink retaining member is formed in advance in a predetermined shape; therefore, when it is compressed into the ink container, the contour of the porous material does not perfectly conform to the internal surface of the ink container, leaving gaps between the two, which is liable to fail to create the capillary force expected there. Further, urethane form, a typical porous material, is not compatible with certain types of ink, which limits the number of ink choices to be stored in the ink container.
Therefore, the inventors of the present invention made a proposal in a Japanese Laid-Open Patent Application No. 34353/1990 in which the ink supplying efficiency was improved by rendering smaller the sponge pore diameter adjacent to the ink supplying port than in the middle of the ink container. The inventors of the present invention disclosed another invention in a Japanese Laid-Open Patent Application No. 8405/1993, in which a bundle off parallelly bound straight strands of fiber was disposed next to the ink supplying port, which was effective for improving the ink supplying efficiency and reducing the amount of the unusable ink.
There are fiber-based structures other than those described above: for example, the structures disclosed in Japanese Laid-Open Patent Application Nos. 96742/1993 and 104735/1993, in which the direction of the ink movement was changed. In the former invention, a bundle of fiber strands is disposed in contact with the sponge piece, in such a manner than when the ink container is in use, the bundle of fiber strands extends from the bottommost portion to the ink supply port disposed above, whereby the amount of the unusable ink which otherwise ends up remaining in the bottom portion of the ink container is reduced. In the latter invention, the entire internal space of the ink container is filled with sponge, and a bundle of fiber strands is disposed within a portion projecting from the ink container, wherein this bundle of fiber strands constitutes an ink supply passage for supplying the ink to the sponge disposed adjacent to the filter of a recording head.
As described above, the main stream inventions regarding the internal structure of an ink container presumes the presence of the sponge; therefore, they have not reduced substantially the amount of the ink retained unusably in the sponge or have not solved the problem that the ink capacity of the ink container is reduced by the presence of the sponge.
On the other hand, a Japanese Laid-Open Patent Application No. 79882/1994 (corresponding to European Appln. 562,733) discloses a structure in which strands of fiber extending vertically (in the direction of the gravity) are disposed within the ink container to occupy no more than 20% of the internal space of the container so that the ink capacity of the ink container is substantially increased, and also, the ink supplying efficiency is improved. However, in this invention, only a small amount of straight fiber, or the strands of fiber, are arranged merely in one direction.
This Laid-Open Patent Application No. 79882/1994 also discloses a modification, in which nonwoven fabric of polyester, polypropylene, or the like is filled in layers in the ink container. This modification is not different from the original in that it suffers from the problems of the conventional ink container.
Through extensive studies of the inventions described in the foregoing, the inventors of the present invention discovered that the structures disclosed in these inventions barely provided an ink retaining capability, and the strands of fiber collected together in a manner of being bundled as the ink was filled. As a result, the ink was concentrated around the ink supply port, deteriorating the efficiency with which the ink was fed out of the ink container, and also, it was impossible to create stably the negative pressure, which was an important factor in the field of ink jet recording.
The primary object of the present invention is to solve new problems, that is, the insufficient ink delivery, the ink leak, and the like, which are created due to the reduction in the overall ink retaining capability of an ink container, resulting from the decrease of the intervals among the strands of fiber employed as the ink retaining material, which occurs while the ink is filled.
Another object of the present invention is to provide an ink container in which the ink retaining capacity is increased by means of improving the arrangement of the fiber that occupies the internal space of the ink container, wherein this fiber strand arrangement relates to the way the fiber strands contact the internal walls of the ink container, and the way the fiber strands contact each other.
During the making of the present invention, attention was given to a different view point: there is an ink flowability difference between the inner portion of the ink container and the portion next to the container wall. In other words, the relationship between the ink flowability, and the material for the ink container internal wall and fiber strand, which had not been studied formerly, was studied. As a result, the present invention could provide a preferably relationship among the properties of the ink (in particular, pigment-based ink) to be used and the fiber material.
On the other hand, the studies by the inventors of the present invention disclosed that as the influence from the fiber itself, there were changes in properties related to the fiber strand diameter. Thus, the second object of the present invention is to provide an ink container in which this properties change is effectively applied.
Being guided by this second object, the present invention provides a preferable ink container, in which a fibrous member constituted of fiber strands with preferable properties in placed across, and in contact with, a filter disposed on the head or container side; more preferably, an ink container, in which a preferable relationship is provided between the diameter of the fiber strands occupying the major portion of the internal volume of the ink container, and the diameter of the fiber strand occupying the ink supply port side (head side), that is, the outward side, of the internal space of the ink container; and an ink container, in which the resistance of the fiber itself constituting the major portion of the ink flow resistance can be eased.
Another object of the present invention is to provide an ink container manufacturing method, in which a type of fiber strand, which is compatible, in terms of shelf life, with the ink to be used, and is placeable, as the ink retaining member, in the container main body, in such a manner that does not limit the choices of usable ink, can be employed, and simply placed in the container main body.
In order to realize such a manufacturing method, the present invention proposes such a structure in which a region containing the fibrous material is provided at least on the ink supplying side of the ink container, wherein the fiber strand within the fibrous material is deformed within the limit of the elasticity of the fiber material, and is caused to extend in various directions so as to form complex multiple intersections.
With the presence of the above described structure, that is, the presence of the multiple fiber strand intersections and the elastic deformation of the fiber strand, it is possible to prevent the gap between the adjacent fiber strand portions, or fiber stands, from being reduced by the properties of the ink as the ink is filled.
The present invention also proposes an ink container structure in which a region containing the fibrous material is provided at least on the ink supply side, wherein the material for the container wall and the material for the fiber strand satisfy the same requirements.
According to the structure described above, the properties of the container wall can be matched with the ink flowability within the fibrous member placed in the ink container; therefore, it is possible to prevent such a phenomenon that occurred in the past that is, the phenomenon that the ink flow along the container wall became excessively different from the ink flow within the center portion of the container, disturbing thereby the flow of the ink or air, and as a result, the amount of the ink left unused increased, or the ink consumption fluctuated.
Also, the present invention proposes, as the manufacturing method for the ink container comprising the container main body filled with the fibrous member capable of retaining the ink, to guide the fiber strand into the container main body as the fiber strand is continuously produced using a fiber strand manufacturing apparatus. With the employment of this method, the fiber and ink container can be manufactured through a continuous operation, making it possible to eliminate the storage facility or the like for the fiber.
The present invention proposes, as another manufacturing method for the ink container comprising the container main body containing the fibrous member capable of retaining the ink, a method in which the fiber strand is formed in advance into a belt of fibrous aggregate, and then, the thus formed belt of the fibrous aggregate is folded into the container main body. With the employment of this proposals, it is possible to place reliably the fibrous member in the container main body while preventing the fiber strand from scattering.
Further, the present invention proposes to place in the container main body a predetermined number of fibrous aggregate pieces constituted of the aforementioned aggregated fiber strand. In this case, their number is varied depending on the type of the ink container in order to match the ink container type.
The present invention also proposes, as a form of the fiber strand arrangement in the container main body, to pack in advance the fiber strand in an ink-permeable pouch, and then, place a predetermined number of the pouches filled with the fiber stand in the container main body. When this method in employed, the fiber strand can be reliably placed in the container main body within being scattered.
It should be noted here that using the polyolefinic material as the fiber strand material is more preferable; in this case, it is possible to give the fiber strand compatibility, in terms of shelf life, with various types of ink, for example, alkaline ink, and also, to stabilize the structure of the fibrous aggregate using the thermoplastic properties of the material.
It is also preferable to place two or more types of fiber strands, which are different in external diameter or sectional configuration; in this case, it is possible to give the fiber strand an optimum ink retaining capability correspondent to its position within the container main body.
Further, as another manufacturing method for an ink container comprising the container main body containing the fibrous member capable of retaining the ink, the ink may be placed in the container main body before the fiber strand is placed therein. Such a manufacturing method allows some flexibility in the order of the manufacturing steps.
Further, the present invention proposes, as another method for the ink container, to increase, when the ink is placed in the container main body, the amount of the ink solvent by the amount equivalent to the amount of the ink solvent that is expected to evaporate while the ink is placed in the container main body.
In this case, the ink solvent may be placed in the container main body before the fiber strand is placed in the container main body.
With the employment of such a manufacturing method, it is possible to prevent the ink from being denatured, to adjust the fiber strand arrangement, in the ink solvent, and to improve the wettability of the fiber strand surface to the ink.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.